Patent Application
20210356123
The present invention relates to a totally aerated combustion burner having a burner body which is supplied inside thereof with an air-fuel mixture, and a combustion plate part which covers an open surface of the burner body and through which the air-fuel mixture is ejected.
As this kind of totally aerated combustion burner, there is known in patent document 1 an arrangement in which the combustion plate part is made up of; a burner frame having in a central part thereof an air-fuel mixture passage region and an enclosing frame part around the air-fuel mixture passage region; and a member permeable to the air-fuel mixture (hereinafter called “an air-fuel mixture permeable region”), the air-fuel mixture permeable member which is made of heat-resistant fibers and which covers the air-fuel mixture passage region of the burner frame. In this arrangement, the burner frame is of a picture frame and has a single opening in the air-fuel mixture passage region for the air-fuel mixture to pass therethrough.
In addition, according to the above-mentioned arrangement, in order to prevent the burner frame from getting overheated by heating with convection and radiation heat from the flame to be formed by the combustion of the air-fuel mixture ejected from the air-fuel mixture permeable member, the enclosing frame part of the burner frame is provided with a thermal insulation material in order to cover the enclosing frame part from the side opposite to the burner body. By the way, the thermal insulation material is fixed by a fixing frame that is spot-welded in advance to that surface of the enclosing frame part which is opposite to the burner body.
However, in the above-mentioned arrangement, the fixing frame and the thermal insulation material are required, bringing about an increase in the number of parts. Also a step of assembling the thermal insulation material becomes necessary, resulting in an obstacle to an attempt to reduce the cost.
In view of the above points, this invention has a problem in providing a totally aerated combustion burner in which the thermal insulation material for preventing the overheating of the burner frame is not necessary so as to be able to attempt a cost reduction.
In order to solve the above-mentioned problem, this invention is a totally aerated combustion burner comprising: a burner body which is supplied inside thereof with an air-fuel mixture; and a combustion plate part which covers an open surface of the burner body and through which the air-fuel mixture is ejected. The combustion plate part is made up of: a burner frame having in a central part thereof an air-fuel mixture passage region and an enclosing frame part around the air-fuel mixture passage region; and an air-fuel mixture permeable member which is made of heat-resistant fibers and which covers the air-fuel mixture passage region of the burner frame, the air-fuel mixture passage region of the burner frame having formed a single opening or a plurality of openings for the air-fuel mixture to pass therethrough. The air-fuel mixture permeable member is disposed to overlap that surface of the burner frame which lies opposite to the burner body. The combustion plate part further comprises a fixing frame which is fixed to that inner peripheral portion of the enclosing frame part of the burner frame which is closer to the air-fuel mixture passage region, in a manner to sandwich the air-fuel mixture permeable member between the inner peripheral portion of the enclosing frame part of the burner frame and the fixing frame. The air-fuel mixture permeable member has an extended part protruding outward beyond the fixing frame so that the extended part covers that outer peripheral portion of the enclosing frame part which is positioned outside the fixing frame.
The air-fuel mixture permeable member is made of heat-resistant fibers and contains therein an air space (cavity). According to this invention, that extended part of the air-fuel mixture permeable member which protrudes beyond the fixed frame functions as a thermal insulating material. Therefore, the burner frame can be effectively prevented from getting overheated. In addition, according to this invention, since there is no need of separately preparing a thermal insulation material, the cost can be reduced.
In this invention, a clearance shall preferably be secured between the outer peripheral portion of the enclosing frame part and the extended part of the air-fuel mixture permeable member. According to this arrangement, due to the presence of the air space inside the clearance, the thermal insulation property relative to the burner frame can be more improved. By the way, if the outer peripheral portion of the enclosing frame part is provided with a plurality of projected parts at a circumferential distance from one another so as to secure the clearance by coming into contact with the extended part of the air-fuel mixture permeable member, the above-mentioned air space can advantageously be stably secured.
By the way, the heat-resistant fibers that are the material of the air-fuel mixture permeable member can be made of metal fibers, but the metal fibers are high in thermal conductivity, resulting in a decrease in insulation characteristics. On the other hand, if the air-fuel mixture permeable member is made of non-metal heat resistant fibers such as SiC and the like, the thermal conductivity of the heat-resistant fibers becomes low. As a consequence, the heat insulation property by the extended part of the air-fuel mixture permeable member can be sufficiently secured.
A combustion apparatus shown in
The heat exchanger 3 is constituted by a fin-tube type of heat exchanger provided with a multiplicity of fins 31 and a plurality of heat-absorbing tubes 32 which penetrate these fins 31. On an outside surface of side plate 23, 24 on laterally one side and the opposite side, respectively, of the combustion box 2, there are provided a plurality of connection covers 33 which define connection passages of the adjacent two heat absorbing tubes 32, 32 between each of the side plates 23, 24. In this manner, all the heat-absorbing tubes 32 are connected together in series with one another. Further, the connection cover 33 defining the connection passage, which is connected to the heat absorbing tubes 32 on an upstream end of the heat exchanger 3, between the side plates 24 of the laterally opposite side are provided with a water inlet 34.
Furthermore, on an inside of that portion of a rear-side side plate 25 of the combustion box 2 which is above the heat exchanger 3, there are disposed vertically arranged three pieces of first water passages 51 made up of tubes in a manner to contact the side plate 25. Also on an inside of that portion of a front-side side plate 26 of the combustion box 2 which is above the heat exchanger 3, there are also disposed vertically arranged three pieces of third water passages 53 made up of tubes in a manner to contact the side plate 26. In addition, on an outside surface of the laterally one-side side plate 23 of the combustion box 2, there are connected: an inlet-side header cover 51 defining, together with the side plate 23, a connection passage which connects the vertically disposed three pieces of first water passages 51 to the heat absorbing tube 32 on a downstream end of the heat exchanger 3; and an outlet side header cover 52 defining, together with the side plate 23, a connection passage for the vertically arranged three pieces of third water passages 53. The outlet side header cover 52 is provided with a hot water outlet 53.
Furthermore, as shown in
Further, the front-side side plate 26 of the combustion box 2 has mounted thereon electrode parts 6 having an ignition electrode 61, a grounding electrode 62, and a flame rod 63 which are protruded through the side plate portion between the two, i.e., the first and the second from the top, of the third water passages 53, 53 into the combustion box 2. The electrode parts 6 are additionally provided with an inspection window 64 through which the inside of the combustion box 2 can be visually inspected.
Detailed description will now be made of the totally aerated combustion burner 1. The burner body 11 has opened therethrough an inlet port 113 for connecting thereto a fan 4 which supplies air-fuel mixture. The inlet port 113 has mounted thereon a check valve 13 which prevents the air-fuel mixture remaining inside the burner body 11 from flowing backward to the side of the fan 4, at the time of stopping of the fan 4. The check valve 13 is made up of; a resin-made valve box 131 which is built into the inlet port 113; and a resin-made valve plate 132 which is rotatably mounted, so as to be opened or closed, in that opening of the valve box 131 which faces inward of the burner body 11.
With reference also to
In an outer periphery of the enclosing frame part 121b of the burner frame 121, there is formed a frame flange part 121d, extended (or protruding) outward, including a stepped part 121c that is bent toward the burner body 11 side (upward). In this arrangement, the frame flange part 121d is sandwiched between the body flange part 112 and the box flange part 22, and further a packing 7 is interposed between the frame flange part 121d and the body flange part 112, thereby securing sealing properties. By the way, as clearly shown in
Now, in case overheating happens to the burner frame 121 due to the heating by convection and radiation heat from the flame to be formed by the combustion of the air-fuel mixture, when the heat transfers from the burner frame 121 to the burner body 11, the burner body 11 will be elevated to a considerably high temperature. As a consequence, a bad effect will be inflicted on the check valve 13 which is an accessory part to the burner body 11. In this case, in order to impede the heat transmission from the burner frame 121 to the burner body 11, it is considered to make the packing 7 of a ceramic packing that is superior in thermal insulation characteristics. This solution, however, brings about a higher cost. In order to enable to use an ordinary packing as the packing 7, it becomes necessary to prevent the burner frame 121 from getting overheated.
Therefore, in this embodiment, the combustion plate part 12 further comprises a fixing frame 123 which is fixed to an inner peripheral portion 121bin, near the air-fuel mixture passage region 121a, of the enclosing frame part 121b of the burner frame 121, in a manner to sandwich the air-fuel mixture permeable member 122 between the inner peripheral portion 121bin of the enclosing frame part 121b of the burner frame 121 and the fixing frame 123. The fixing frame 123 is circular and is provided, at a circumferentially plurality of positions thereof, with drawn parts 123a which protrude toward the burner frame 121 side (i.e., upward). In this arrangement, by inserting these drawn parts 123a into each of holes 122a formed in the air-fuel mixture permeable member 122, the drawn parts 123a are then spot-welded to the inner peripheral portion 121bin of the enclosing frame part 121b. The fixing frame 123 is thus fixed to the inner peripheral portion 121bin of the enclosing frame part 121b. According to this arrangement, the air-fuel mixture permeable member 122 will be sandwiched between the enclosing frame part 121b and the fixing frame 123 at a portion other than drawn parts 123a of the fixing frame 123.
The air-fuel mixture permeable member 122 is provided with an extended part 122b that protrudes outward beyond the fixing frame 123. It is thus so arranged that the extended part 122b covers that outer peripheral portion 121bout of the enclosing frame part 121b which is positioned outside the fixing frame 123. It is to be noted that the air-fuel mixture permeable member 122 is made of heat-resistant fibers and contains therein air space (cavity). Therefore, that extended part 122b of the air-fuel mixture permeable member 122 which covers the outer peripheral portion 121bout of the enclosing frame part 121b functions as the thermal insulation material. Overheating of the burner frame 121, specifically an excessive temperature rise of the frame flange part 121d of the burner frame 12, can effectively be prevented. Therefore, it is not necessary to use, as the packing 7, an expensive one that is superior in thermal insulation property. Further, an insulation material need not be specially provided for the purpose of preventing the burner frame 121 from getting overheated, thereby contributing to the cost reduction.
By the way, it is also possible to replace the heat-resistant fibers as the material for the air-fuel mixture permeable member 122 with metal fibers. However, metal fibers are high in thermal conductivity and the thermal insulation property lowers. Therefore, the air-fuel mixture permeable member 122 shall preferably be made to be heat-resistant fibers of non-metal such as SiC and the like. According to this arrangement, since the thermal conductivity of the heat-resistant fibers becomes lower, thermal insulation property by the extended part 122b of the air-fuel mixture permeable member 122 can advantageously be sufficiently secured.
Further, according to the second embodiment as shown in
Descriptions have so far been made of the embodiments of this invention with reference to the figures, but this invention shall not be limited to the above. For example, in the above-mentioned embodiments, the burner frame 121 has formed therein a plurality of openings 121a′ made up of small holes. However, it is also possible to form a single opening over the entire region in the air-fuel mixture passage region 121a. In this case, there may be arranged such that a distribution plate in which a plurality of small holes corresponding to the openings 121a′ in the above-mentioned embodiment overlap that surface of the air-fuel mixture permeable member 122 which lies on the burner frame 121 side. In addition, in the above-mentioned embodiment, the burner frame 121 is made of a metal plate, it may alternatively be made of a material other than the metal plate such as made of aluminum die-cast product and the like. Further, the totally aerated combustion burner according to the above-mentioned embodiment is disposed such that the open surface 111 of the burner body 11 faces down. However, this invention is similarly applicable to the totally aerated combustion burner disposed such that the open surface 111 thereof faces up.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-084714 | May 2020 | JP | national |
